1. Field of the Invention
The invention relates to a magnetic disk memory device, and more particularly, to a head contact type magnetic disk memory device having a novel magnetic head slider for providing stable head contact to a disk surface, while keeping low loading during recording and reproducing operations.
2. Description of the Related Art
Recently, a head contact-type magnetic disk memory device has been developed in order to increase recording density on a magnetic disk. The head contact-type magnetic disk memory device includes a magnetic head slider for sliding on a surface of a magnetic disk, and for bringing a magnetic head into contact with the disk surface during recording and reproducing operations.
Usually, the magnetic head slider has a slider surface facing a disk surface. During recording and reproducing operations, the slider surface is subject to air pressure caused by fluid dynamic pressure effects due to relative motions between the head slider and the rotating disk surface. In order to utilize the air pressure effects during the rotation of the magnetic disk, a portion of the head slider is designed so as to contact the disk surface as a result of the air pressure during recording and reproducing operations. Usually, a back end portion of the slider surface along a forward-moving direction of the head slider remains in contact with the disk surface.
In order to prevent hard wear on the contact pad to a disk surface, it is necessary to keep low loading during recording and reproducing operations. As illustrated in FIG. 17, assuming that a head slider 100 has a contact pad at an air flow outlet edge and a positive pressure generating part, a contact force is fc, the suspension load is F, a positive pressure is fn, a distance between fc and F is lg, and a distance between fc and fn is ln, the following formula applies:
fc=(lhxe2x88x92lg)/lhxc3x97F 
In order to realize the smaller contact force, a configuration of the magnetic head slider is proposed as illustrated in FIGS. 18A and 18B. The head slider 100 includes a positive pressure generating part 106 at an air flow inlet edge and a contact pad 107 that generates almost no positive pressure at an air flow outlet edge. The suspension load position is almost the same with the positive pressure generating part 106. A positive pressure on the positive pressure generating part 106 is almost the same with the suspension load F, and almost no positive pressure is generated on the contact pad in this configuration. Consequently, this configuration has a short distance lnxe2x88x92lg, and a long distance ln, so that the small contact force is achieved.
As illustrated in FIGS. 18A and 18B, both the positive pressure generating part 106 and the contact pad 107 are positioned at a top surface A of the head slider. Namely, the surface A of the slider is the closest to the facing disk surface. Each of the surfaces A, B and C of the head slider has a different height relative to the disk surface. But such a small contact pad has no cushion effect by air-bearing forces against shocks during a head loading operation. Consequently, the contact pad hits hard on the disk surface and is worn by hits in a head loading operation.
The head contact-type magnetic disk memory devices are usually installed in handheld devices, such as notebook-type personal computers. To apply the head contact-type magnetic disk memory device in a handheld computer, it is desirable that stable head loading and unloading operations be performed along with restricted fluctuations of the contact force of the magnetic head caused by shocks to the computer. Thus, it is desirable to keep a stable contact between the head slider and the magnetic disk with a low load. Further, it is needed for the computer use to enhance the suppression of contact force fluctuations on the slider caused by changes in atmospheric pressure.
Therefore, there is a need for providing a head contact-type magnetic disk device having a novel magnetic head slider that can perform a stable head contact to a magnetic disk with a low load in order to restrict the variations of the head slider contact forces.
In order to overcome the above-mentioned problems and disadvantages of conventional devices, the invention provides a magnetic head slider having an air flow inlet side, an air flow outlet side, and a plurality of surfaces between the inlet side and the outlet side for constituting fluid force generating parts for the magnetic head slider, due to dynamic pressure effects of the air flow accompanying rotation of the magnetic recording medium. Each of the plurality of surfaces has a different height level for respectively defining a different distance to a surface of the magnetic recording medium. The magnetic head slider comprises: a contact pad for supporting a magnetic head for recording and reproducing data to and from a magnetic recording medium, so as to make the magnetic head contact the surface of the magnetic recording medium. The contact pad is provided around the air flow outlet side at a top level in the plurality of different height levels. A positive pressure pad area is provided around the air flow inlet side for generating positive pressure during rotation of the magnetic recording medium, and the positive pressure pad area is positioned so as to keep the same top level of the contact pad. A squeeze pad area is also provided for suppressing fluctuations of contact forces between the magnetic head and the magnetic disk medium, and the squeeze pad area is provided along the air flow direction at a middle height level between the top level and the low level of the surfaces so as to cross the low level of the surfaces.